[GUI Functional testing/Taurus] Added ability to pass browser options via YAML file

During GUI Functional testing, you may need to configure your browser for specific cases, like emulating mobile devices in the browser, or emulating web cameras and many more. This can be achieved by passing appropriate browser options/arguments, or even experimental options. The Taurus YAML file syntax now allows you to pass such options to the browser: https://gettaurus.org/docs/Selenium/#Browser-Options

[GUI Functional testing] New browser versions now available 

We’ve added new browser versions including Chrome version 90, and Firefox version 88. These versions are set as default.